Javascript variable to PHP variable - Post if statement isnt working

my

if(isset($_POST['height'])){

is just going straight to

else{}

what is the reason for this?. so basically it's suppose to detect the height of a div. Send it back to the PHP where it is compared to 1 and echo different statements depending on the product. I am wanting to keep it AJAX so that I am able to do detect the height of a div and send it to a PHP if statement without having to refresh the page. if you have any idea what's going on it would be much appreciated. papa bless.

PHP

<?php

if(isset($_POST['height'])){
$solo_height = $_POST['height'];

if ($solo_height > 1){
//HERE YOU SHOULD ECHO BACK A RESPONSE TO THE AJAX CALL
echo '<div class="view_full_post">View Full Post</div>';
// WHAT DOES $this->output($var); DO??? I HAVE NO CLUE...
// SO JUST ECHO THE DIV JUST FOR TESTING...
}else{
echo "The Height is Less than a Thousand... What do we do sir???";
}
}
?>

Ajax

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script>
(function ($) {
$(document).ready(function(e) {
view_height = $("#view_height").height();
$.ajax({
type: "POST",
url: "index.php", // POINTS TO THE PROCESSING FILE WE CREATED ABOVE
data:{ height: view_height },
success: function(data){
console.log(view_height); // NOW YOU SHOULD BE ABLE TO GET A RESPONSE....
// UPDATE THE DIV THAT YOU WANTED TO...
// ==> HERE IS THE NEW UPDATE REFLECTING YOUR USE CASE:
// ==> ADD THE DIV RIGHT AT THE TOP OF THE BODY ELEMENT...
},

<?php
if(isset($_POST['height'])){
$solo_height = $_POST['height'];
if ($solo_height > 1){
echo '<div class="view_full_post">View Full Post</div>';
}else{
echo "The Height is Less than a Thousand... What do we do sir???";
}
}
?>